Zemer Gitai New Innovator Award Application Area of Science: 07: Molecular and Cellular Biology Title: Discovering Antibiotic Drugs & Targets Via High-Throughput Bacterial Cell Biology Abstract: The rise of antibiotic resistance in bacterial pathogens represents an escalating global health crisis. We will help tackle this problem by applying our expertise in high-throughput imaging and bacterial cell biology to identify and characterize both new families of proteins essential for bacterial viability (candidate drug targets) and small molecules that perturb these proteins (candidate drugs). This proposal builds upon our previous development of methods to analyze protein localization that are fast, easy, and affordable enough to be routinely re-applied on a genomic scale. We have already used this high-throughput pipeline for generating, imaging, and quantitatively analyzing fluorescent protein fusions to determine the localizations of over 3,250 proteins in Caulobacter crescentus, a unique polarized model bacterium, identifying over 300 new localized proteins. We now propose to harness these resources to identify new antibiotics and antibiotic targets. First, we will combine our localization library and high-throughput imaging methods to screen for antibiotic compounds that inhibit the localization and function of known essential localized proteins, such as bacterial cytoskeletal elements. As a promising proof of principle, we have characterized a small molecule that targets the bacterial actin-like cytoskeleton and can block the growth and virulence of a wide range of human pathogens. We will use our new methods for high-throughput high-resolution microscopy to screen for compounds that perturb the localization of the MreB actin homolog, the FtsZ tubulin homolog, and the ParA cytoskeletal ATPase. These proteins are all localized, essential, and very widely conserved among human pathogens. Second, we will combine our recently-completed screen for new localized proteins with traditional molecular genetic techniques to identify and characterize novel families of proteins that are localized, conserved in pathogens, and essential. These proteins will represent excellent targets for future chemical screens to find new classes of antibiotic compounds.